Spark-plug structure



July 30, 1929. o. K. BoGsTRAND SPARK PLUG STRUCTURE Filed March 1o, 1926 Patented July 30, 1929.

v ignara OLE K. BOGSTRAND, OF BROOKLYN, NEW YORK.

SPARK-PLUG STRUCTURE.

Application filed March 10, 1926. Serial No. 93,561.

My invention relates to spark plug structures for use in gasoline and other internal combustion engines employing the jump spark system of ignition. l

Une object of my invention is to provide a spark plug which causes sparks to occur at a plurality of points throughout the explosive mixture resulting in a more perfect combustion of the mixture with the consequent elimination of the objectionable deposits due to unburnt carbon particles.

Another object of my invention is to provide a spark plug employing a plurality of .series gaps so that should one of the gaps be bridged by a carbon particle and be rendered ineffective, the other gaps would nevertheless be Operative and the plug would still function.

A further object of my invention is to provide a spark plug in which the primary and secondary coils are imbedded directly in the structure of the plug itself.

Another, and important, object of my invention is to construct a spark plug having associated therewith a simple and effective means for priming the engine.

Still another object of my invention is to provide a spark plug having a plurality of gaps, in which means are provided for readily and conveniently cleaning the gaps.

Further objects of my invention will in part be apparent and will in part be pointed out in the description of the accompanying drawings, in which I have disclosed one modification of my invention. However, I do not intend to be limited to the details of construction disclosed but intend to cover all such modifications as will readily occur to one skilled in this art and as fall within the scope of the appended claims.

In the drawings Figure 1 is a sectional elevation view on the line 22 of Figure 4;

Figure 2 is a view of a part of the spark plug looking at the spark plug from the left of Figure 1;

Figure 3 is a view of a part of the spark plug looking at the spark plug from the right of Figure 1 Figure 4 is a sectional view taken through the plane indicated by lines 3-3 of Figure 1; and

Figure 5 is a diagrammatic viewillustrating certain features of the invention.

In the drawings, the numeral 1 indicates the metal casing of the plug. This casing is reame'd to form a bore in which the porcelain insulator 2 slidably iits. The porcelaininsulator seats upon the projection 3 on the in-v ternal surface of the metal casing and is securely held in position by gland nut 4. A flexible washer 5 is employed to insure gas tightness. The metal casing of the plug is externally screw-threaded and screws into the metal bushing 6. The bushing 6 is inserted from the inside of the engine into a suitable hole in its casing.

The porcelain insulator is provided with a bore for the reception of the primary coil 8 and secondary coil 7 'of the ignition system. Current is fed to thepriinary coil from the lead wire 9 through a spark intensifier 10 of well known construction. A metal flange 11 is secured to the end of the concentric coils 7 and 8, one terminal of the primary coil 8 being electrically connected thereto, the other terminal being electrically connected to the inet-al casing of the plug in any suitable manner and grounded through the casing of the engine. The terminal lug 12 of the feed wire for the primary is seated on the flange 11, and clamped thereon, by means of the screw 13, bushing 14` and nut 15, the bushing and nut being threaded on the screw as shown in Figure 1. The handle 16 on the end of the Screw 18 enables it to be screwed into the iange 11. A metal washer 17 is preferably interposed be-` tween the nut 15 andlug 12.

One/terminal of the seconda-ry coil 7 is connected to the metal casing of the plug in any suitable manner and grounded through the engine casing. rlhe other terminal is connected to a ring or disc 18 which serves as the first or initial electrode in the series multi-gap arrangement hereinafter described. Below the ring electrode 18 are a plurality of spaced disc electro-des 19, 20, and 21 which are provided with projecting nibs 22 to 26, serving as discharge points. The electrodes 19, 2O and 21 may be spaced apart by any suitable means, insulating washers 27, 28 and 29 being' 1 preferably employed for the purpose. The

lower electrode 25 of the stacked discs is provided with a projecting hollow cylindrical portion 80, the end of which is spaced at a short distance from the horizontal electrode 81. The electrode 31, is shapedas shown in Figure 4 and is supported from the porcelain by the arms or lugs 32, ,33 which are preferably integrally formed with the electrode 31 and the ends of which are embedded directly in the porcelain. Supported from the metalv casing, 1, of the spark plug, but insulated therefrom in any suitable manner, are

the horizontal spiral electrodes 34, and 36,

Figures 1 and 5.' This structure preferably v,comprises three horizontally iadiatiiig arms 39, and 41, arranged at angles of about 120 degrees apart. The number of arms, of course,;may be varied as desired. Each arm is 'composedof a metallic casing which is integrally formed i 1ith the bushing 6. lilithin the arm 39 there is carried the two conducltors 42 and 43 which are parallel to and insulated from one anotherfas by being embedded in anv insulating substance 47. The conductor 42 is connected electrically to the gasoline' cup. A small electrode 44 is supported adjacent the ends of yconductors and 43 and Sis spacedtherefroin to form gaps therewith. Similarly the arin 40 comprises two conductors 45' and 46, supported in the insulator 47, and an electrode 43 spaced from the' ends of the conductors.

4Between the conductor 43 in arm 39, and 'conductor 45 in arm 40, there is a small gap 49. The arm 41 lhouses an insulator in which there is einbedded the conductor 51 which'is spaced from the conductor 46 in arm 40 to form a gap 52. Supported by the metal casing of the arin 41 at a slight distance from the end of 'conductor 51 is the electrode 53 which is ground- Ved through the metal casing of arm 41, bushing 6 and the engine casing.

The operation is as follows: lVhen a culrent of sufioient potential is induced in the secondary 7, the series gaps break down and discharge occurs across the gaps between Vertical electrodes 19, 20, 21, across the gaps formed by the spiral electrodes 34, 35, 3G, from nib 37 to the gasoline cup, thence through the radiating arm structure across l the gaps therein to ground through the engine. l

Itwill be 'noticed that the sparks occur at many points 'and are widely distributed and the result isvthat 'combustion is Very rapid Vand complete. Moreover, should any of the gaps bev bridged by particles of carbon the spark plug would still function as the cur rent would 'pass through the carbon and cause sparks at the remaining gaps in series with the short-circulated gap or gaps.

'Furtherinore, the resulting` explosion would tend .to burn olif the deposit of carbon or oil ifisasee and restore the inoperative gap to full efl fe'ctiveness.

The gas cup, 33, affords a simple means for priming the engine. This cup may be filled with gasoline by unscrewing the screw 13 'and pouring the gasoline through the opening in coil 7 and the openings in the disc electrodes 19, 20, 21.

Means are provided by which the gaps between the vertically stacked electrodes 19, 20, 21, vcan vbe cleaned. The means preferably take the form of horizontal holes shown in dotted line in Figure 1 opposite to the gaps and extending through the porcelain and iiietal easing of the plug. A cleaning tool can be inserted through theholes to cleanthe su 1faces of the electrodes.

The spark plug may also be cleaned by blowing olf drops of oil or water or particles of carbon or dirt between the gaps. For this purpose the screw 13 is removed and the engine turned over by a starter or otherwise, so that on the compression stroke the gases will escape through the opening in the bushing 14 andV carry the deposit with them. In order that it may not be necessary to entirely remove the plug 13 to blow olf the deposits as above described'or prime the engine, the plug is provided with a hole 13 extending partially therethru as shown in .Figure 1.

By unscrewing the plug a suitable distance,

the passage 13" willv register simultaneously with the atmosphere and with the interior of the plug. y

Y ln assembling the above described structure the bushing 6, and Vparts associated therewith, comprising the radiating arms and gasoline cup, are inserted from the inside of the engine cylinder and the bushing 6 screwed into a suitable hole in the casing ofthe en gine. ylhe metal casing 1, which houses the porcelain core, induction coils and stacked electrodes,'is then screwed into the bushing 6, from the exterior of the engine. 1t will be obvious that it would be possible, if desired, to use only the casing land associated parts, and dispense entirely' with the bushing 6 with its radiating arms. In this case the final electrode of the spiral series of gaps would be grounded to the casing 1 instead of beinginsulated therefrom, and the casing 1 would be screwed into the customary spark plug aperture in the engine casing.

Wlhat I claim is:

1. ln a spark plug structure, a tubular bushing, a plurality of radiating arms containing spark gaps supported by said bushing and a cup supported at the axis of the radiating arms.

2. ln a spark plug structure, a tubular bushing, a plurality of radiating arms containing electrodes supported by said bushing, a hollow metal casing adapted to be rinserted in said bushing, a porcelain core within the casing, a. plurality of spaced spil-ally shaped electrodes supported by the core and the metal casing, and a cup supported beneath the spirally shaped electrodes at the axis 0f the radiating arms,

3. In a spark plug structure, a hollow7 inetal casing, a porcelain core having a recess Within the casing, a plurality of vertically spaced electrodes Within the recess, said electrodes having vertically aligning central openings, and a cup supported beneath the 10 aligning openings.

In testimony whereof, I have signed my naine to this specification this 6th day of March, 1926.

OLE K. l BOGSTRAND. 

